The purpose of our research was to explore the shape bias of adults in hypothesis testing task. Geometrical figures were used in our study which contained three dimensions (shape, color and pattern). The testing stimuli could be classified into two groups (1S and 2S) according to their si-milarity with the testing objects. 1S shared one feature with the testing objects, while 2S shared two features with the testing objects. It was found that: 1) adults preferred 2S, suggesting that si-milarity plays an important role in the process of induction; 2) compared with color, adults showed shape bias based on similarity, indicating that shape was an critical clue for the induction of adults.